Electron discharge device employing cavity resonators



May 9, 1950 2,506,752

R. TRUELL ELECTRON DISCHARGE DEVICE EMPLOYING CAVITY RESONATORS Filed July 22, 1944 2 Sheets-Sheet 2 van vaunrnnauunnuuuannuau INVENTOR H -fi Rom: TRUELL 7 @45 ATTORNEY tor having a small width gap adjacent the beam path but having a large aperture for permitting a large beam current to flow through the resonator.

Between the resonator and the reflector is a second electrode which acts as a focusing electrode and comprising two ring-like elements 30-- 3! electrically connected together by means of the conductor 32. All of these electrode e le ments and circuit elements are maintained in fixed spaced position by means of the glass bead support construction indicated at 33, 34, 35 and 36. There may be several groups of these, preferably three groups. The reflecting electrode I! may be provided with lead 31 and the cathodeheater with leads 38 and 39 for supplying heater current to the cathode heater I3, which is insu-' lated from the cathode by means of an insulating coating.

It will thus be apparent that a large beam current can be directed toward the reflecting electrode M. The cathode has a very large emitting area and due to the fact that the transverse cross section of the beam becomes less as the reflecting electrode is approached, the current density increases, thus resulting in two factors which increase the power output of the tube, that is a large current of high current density.

The output may be taken from the cavity resonator by means of the coaxial line or wave guide 40-4! having a loop 44 at the cavity end. This line passes through support 42 sealed to the envelope, the coaxial line being hermetically scale in the support at 43.

As best shown in Figure 3, the cathode heater j I3 is supplied from the voltage source at 50 and the voltage source for the various other electrodes is indicated at 5|. It will be observed that the resonator 22-23 is maintained at the highest positive potential while the reflector I4 is maintained at negative potential less than the cathode I2, the electrode l9 being maintained at a more negative potential for properly focusing the v beam. The voltage between'the cathode and the cavity resonator may be of the order of 1500 to 2000 volts.

In the operation of the device, electrons from the cathode l2 are focused by the ring electrodes |920 through the resonator gap where they are velocity modulated in conventional man-' ner by the oscillatory field in the resonator. After passing through the resonator gap, the electrons approach the negative reflecting electrode l4 and are reflected thereby back through the resonator, being focused by the ring electrodes |920 as they pass therethrough. During their transit from the resonator toward the reflecting electrode and back, the electrons form bunches which, in passing back through the resonator, drive the resonator at its resonant frequency to render the device self-oscillatory.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed," it will be apparent that my invention is by no means limited to the exact forms illustrated-or the use indicated, but that many variations may be made in the particular structure used and'the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having means face for supplying and directing a stream of electrons converging toward the axis of curvature of said surface, an electrode positioned at said axis, a curved cavity resonator positioned between said cathode and said electrode and having a gap therethrough of relatively-small beam area compared to the area of said emitting surface in the path of said converging beam, and focusing electrodes spaced from said cathode, electrode and resonator and positioned between the cathode and cavity resonator and between the cavity resonator and the electrode at said axis, each of said focusing electrodes comprising a pair of axially-spaced curved elements providing a gap between the adjacent edges thereof through which the path of said converging beam lies,

'whereby the electron density in the beam will be substantially greater in said gap than adjacent said cathode.

2. An electron discharge device having a cathode for supplying a stream of electrons, an electrode toward which said electrons are directed, and a cavity resonator positioned between said cathode and said electrode and including a solid conducting element having a recess formed in one surface thereof and adjacent the beam path, and a conducting member extending transversely of the beam path and positioned on said conducting element and extending over the recess and forming therewith a cavity resonator, the edges of said element and said member adjacent the beam path forming a gap past which said electrons are directed during operation of said device.

3. An electron discharge device having means including a, cathode of annular shape for directing a stream of electrons radially inwardly toward the axis of said cathode, a first electrode positioned at the axis of said cathode, an annular cavity resonator positioned between said cathode and said electrode and having a gap in the path of said electron stream, and a focusing electrode comprising a pair of axially-spaced anjnular elements positioned between and spaced 1 from the cathode and cavity resonator and pro viding a gap between the adjacent edges of said annular elements through which the path of the stream of electrons lies.

'the axis of said cathode, an annularly-shaped cavity resonator positioned between said cathode and said electrode and having a gap in the path of said electron stream, and electrodes of annular v shape positioned between the cathode and cavity resonator and between the cavity resonator and the electrode positioned at said axis, each of the annularly shaped electrodes comprising a pair of axially spaced ring members providing a gap between the adjacent edges of said ring members,

the path of the stream of electrons passing through each gap.

5. An electron discharge device having means including a cathode of annular shape for directing a stream of electrons radially toward the axis of said cathode, an electrode positioned at the axis of said cathode, and an annularly shaped cavity resonator positioned between said cathode and said electrode, and electrodes of annular shape positioned between the cathode and cavity resonator and between the cavity resonator and the electrode positioned at said axis, each electrode of annular shape comprisincludingacathode havingacurved emitting-surin a Pair f axi lly Sp ced rin -members pr viding a gap between the adjacent edges thereof, the path of the stream of electrons passing through each gap, said cavity resonator comprising a pair of axially spaced comparatively thick ring-like members each having an annular recess adjacent the path of the stream of electrons and. a ring-like element extending over each recess to form therewith a cavity resonator, the edge of said thick ring-like member and the edge of the ring-like element extending over said recess providing a gap past which electrons are directed toward the electrode at said axis.

6. An electron discharge device having means including a cathode of annular shape for directing a stream of electrons radially toward the axis of said cathode, an electrode positioned at the axis of said cathode, and an annularly shaped cavity resonator positioned between said cathode and said electrode, said cavity resonator comprising a pair of comparatively thick ring-like members spaced axially and each having an annular recess adjacent the path of the stream of electrons and a ring-like element extending over each recess to form therewith a cavity resonator, the edge of said thick ring-like member and edge of the ring-like element providing a gap past which electrons are directed toward the electrode at said axis.

7. An electron discharge device having means including a cathode of annular shape for directing a stream of electrons radially toward the axis of said cathode, an electrode positioned at the axis of said cathode, and an annularly shaped cavity resonator positioned between said cathode and said electrode, said cavity resonator including a comparatively thick ring-like memher having a recess in the inner wall adjacent one edge of said ring-like member, a ring-like element on the inner surface of said ring-like member and extending over said recess, the edge of said thick ring-like member and edge of said element providing a gap past which electrons are directed toward the electrode.

ROHN TRUE-LL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,108,900 Peterson Feb. 22, 1938 2,151,765 Hollmann Mar. 28, 1939 2,170,219 Seiler Aug. 22, 1939 2,216,170 George Oct. 1, 1940 2,259,690 Hanseletal Oct. 21, 1941 2,409,694 Laidig Oct. 22, 1946 Disclaimer 2,506,752.Ro7m Truell. Princeton, N. J. ELECTRON DISCHARGE DEVICE EM- PLOYING CAVITY RESONATORS. Patent dated May 9, 1950. Disclaimer filed Oct. 4, 1951, by the assignee, Radio orpomtz'on of America. 

